Biochemical Techniques and Instrumentation

2.6.3.2. Injector

Injector port contains a heated chamber into which sample is injected through a rubber septum using microsyringe. Septum purge outlet in the injector port prevents septum bleed components from entering into the column. It is always good to introduce as small a volume for optimum column efficiency. If it is a packed column, inject 1 to 5 μl and a capillary column, inject 0.5 μl volumes. The sample vaporizes in the injector port to form a mixture of carrier gas and vaporized solutes. It is important to maintain the injector at a temperature of about 50°C higher than the boiling point of the least volatile component in the sample mixture. There are two types of injection known as split injection and splitless injection. In split injection mode, a portion of the sample compound mixture passes into the column and rest exit through the split outlet.